"We watched three jet-boats go by and we were waving, with all the children, at them.
''I turned around and when I looked back the jet-boat was upside down and people were lying on the riverbed," she said.
Dr Cottle and her brother, Mike Hurring - who is a surgeon - ran 300m to the crashed jet-boat and waded through waist-deep water to reach the injured occupants.
"Mike yelled out to my parents to keep the kids back.
''We could see that one of the [jet-boat passengers] was dead," she said.
The pair grabbed a first-aid kit which had fallen from the boat and went to work.
Mr Hurring, a former Dunedin man, is a hip replacement surgeon and part-time deputy sheriff in New Orleans.
They spent the next three hours giving first aid to injured English siblings Leanne and Dave Tonney.
Dr Leanne Tonney's partner, Dr Paul Woods, was killed when he was thrown from the jet-boat.
Mr Hurring lay for two hours in the freezing waters of the Matukituki River to comfort the injured Mr Tonney and help keep him warm.
He told jokes and stories to keep the hurt man from falling asleep in the cold river, Dr Cottle said.
The Otago Regional Rescue Helicopter arrived about two hours after the accident to transfer the injured Tonneys to Dunedin Hospital.
Dr Cottle said her heart went out to Dr Tonney over her loss.
She did not think that the actions of herself and Mr Hurring were heroic.
"It didn't seem real.
''Mike and I have the training and we just did what we had to do," Dr Cottle said.
"Anyone else in the same situation would have done the same."
